This invention relates in general to a bias circuit for supplying a given bias voltage and, more particularly, to a temperature-compensating bias circuit which compensates for temperature drift in a transistor circuit that is biased, for instance, an emitter-coupled astable multivibrator.
The operating characteristics of transistor circuits are usually subject to deviations with varying ambient temperatures. For example, the oscillation frequency of an emitter-coupled astable multivibrator involves what is commonly called "temperature drift" and varies undesirably with variations in the ambient temperature. In order to compensate for deviations from the regular operating characteristics of the transistor circuit due to the temperature drift noted above, it has been proposed to construct a bias circuit for supplying a bias voltage which determines the oscillation frequency of a multivibrator, for instance, such that the bias voltage itself involves a temperature drift. With such a bias circuit, the bias voltage generated therefrom and supplied to the transistor circuit can vary with the ambient temperature and cancel out the temperature drift of the multivibrator.
Hitherto, however, it has been difficult to realize a bias circuit of the type noted above which can supply a bias voltage, has a desired temperature dependency, and has a temperature coefficient which is adjustable. Therefore, a prior art bias circuit could not effectively temperature-compensate transistor circuits having various temperature drifts, and it has been impossible to solve the temperature drift problem in such transistor circuits.